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I have a wooden house from 1950, and when I settle on a new piano, I'd like to do a side-by-side comparison with the old one. I'm wondering whether it'll be safe to put them next to eachother or if both pianos will end up falling through to the basement!

BrianDX
1000 Post Club Member
Registered: 04/14/14
Posts: 1192
Loc: First Town, First State

Originally Posted By: Rickster

Interesting...

Luckily, my grand pianos are located in areas with a concrete slab floor... a little more forgiving of the weight of a grand/baby grand.

When my dad built their house years ago, he put the floor joists, wall studs, ceiling joists and rafters on 12 inch centers. It was built like a tank...

I guess they don't build new houses nowadays with the idea of having the floor support a real grand piano.

All in all my house which is only two years old is actually pretty well built. The problem is, the exact spot where the piano sits could not be worse from where the structural elements underneath are located.

My contractor told me today he has worked with a person who spent over 10 grand to completely redo his third floor townhome floor in order to support an 1100 pound grand piano.

I'm actually not all that upset and not too surprised to be honest. However, it it a consideration to anyone thinking of bringing in a heavy instrument as to where it will go, and how well the floor system will perform underneath it.

The problem is that the weight distribution of four people is very different than the effect of the weight channeled to three, very small contact locations. Also, the legs happen to be on the plywood sub-floor, rather than on the joists.

BDB - You are confusing the floor framing, the joist support system, with the 3/4" plywood sheeting/decking placed on top. Having the plywood splinter and/or deform at a given point is hardly the same as a total collapse. It is highly unlikely that the piano is about to go crashing into the basement.

The piano should not splinter 3/4 inch plywood, cross bracing should help with the bounciness though. I assume the added pillar going under a support beam? I would have thought the cross bracing itself would have done the trick, or at least have been something to try first.

If the subfloor is 3/4" "plywood" and not "oriented strand wood", (also known a "beaver barf", thank you Rod Verhnjack), it will support a grand piano no problem. The flexing you are noticing when you walk on the floor would occur without any piano.

If the "concrete base floor" is in the crawl space-installing a post with proper earthquake ties and moisture barrier under a joist at the center of the floor would stiffen things up greatly. This should cost less than $500 for a handyman who understands moisture and earthquake issues. If you need a beam under the joists-that will cost much more.

It is wouldn't be very aesthetic but as a temporary solution a two-by-four under each leg would distribute the load over a larger area of the floor and maybe if the boards are long enough and angled perpendicular (90 degrees) to the direction of the vibration it would be reduced.

The problem is that the weight distribution of four people is very different than the effect of the weight channeled to three, very small contact locations. Also, the legs happen to be on the plywood sub-floor, rather than on the joists.

Now you've got me thinking about a pair of very large ballet dancers performing a lift...

_________________________Ladies and Gentlemen: This is not a competition, merely an exhibition. No wagering please.

We sometimes get a similar problem with snooker tables, which are a good deal heavier than even the heaviest grand piano.

I am pleased with my music room. The original floor is on huge oak beams. The boards are not good so I covered those with pine tongued and grooved boards 25mm thick. The piano hadn't fallen into the basement last time I looked.

BrianDX
1000 Post Club Member
Registered: 04/14/14
Posts: 1192
Loc: First Town, First State

The good news is that this problem is more of an annoyance than anything else right now. Whenever someone is playing the other (usually me) tip-toes around to my office.

Other than being a pain in the you-know-what, I'm concerned that this extra vibration will not help the stability of my C2X when it comes to staying in tune. Now I could be completely wrong about this...

My first house was a wood house, up off the ground. Built in the forties. I didn't have a piano at the time, but I did have a six foot long marble pedestal table. The pedestal was about 15x24 or so.

I was worried about it, but the table actually made things more stable. Previously, things would rattle when I walked around but after I brought it in, all that stopped. It was still more rattle-ish than a slab, but not by much.

PaintedPostDave
500 Post Club Member
Registered: 06/09/10
Posts: 616
Loc: Upstate New York

"Fully insulated 5 foot high crawlspace." That is good news. It means you can probably support the joists nicely with the 2x12s. How many feet do the joists span? And what is the dimension in the other direction perpendicular to the joists? Finally, are the joists 2x8 or 2x10's.

The joists in my 110 year old house are 2x8's and span 16 ft (the 2x8s are actually 2 inches thick). When I moved in I did not notice much give in the floor but I hate to feel the floor move in any way when I walk across it so I effectively halved the span by adding my own beams.

I built up beams from three 2x4s side by side. I glued them and also bolted them together to make a solid 4 1/2 (w) by 3 1/2 (h) beam that was 8 ft long. I supported each beam by two metal cellar posts from Home Depot. I put the beams under (and perpendicular to) the joists throughout the basement. My only costs were the 2x4s and the cellar posts.

This was way before I bought the Knabe grand. The addition of the piano had no noticeable effect. I also put steel plates under the piano feet so as to distribute the force over a larger area and decrease the localized floor pressure (floor pressure is pounds force per square foot).

So, it sounds like your addition of the 2x12s will effectively cut the span in half and solve the problem. Good luck.

Half the span means a quarter of the deflection -- or even better in this case, as you're making the joists into continuous beams. Adding a girder and some piers and posts should do the trick for the OP.

BrianDX
1000 Post Club Member
Registered: 04/14/14
Posts: 1192
Loc: First Town, First State

Originally Posted By: JohnSprung

Originally Posted By: PaintedPostDave

"...so I effectively halved the span by adding my own beams.

Half the span means a quarter of the deflection -- or even better in this case, as you're making the joists into continuous beams. Adding a girder and some piers and posts should do the trick for the OP.

A quarter of the deflection would be just fine.

I noticed last night that even though only a part of the support system is in place, the floor movement is already down by a third in my estimation. The entire 25 square foot floor system directly under the piano is now one continuous support structure.